what happened to jimmy hoffa, the union boss who disappeared 37 years ago? there have been all kinds of rumors about where he ended up, and now, thanks to a death bed tip, this mystery might soon be solved. abc's john donvan is on the beat. >> reporter: following a tip from a dying man, police are looking at this property in roseville, michigan, at the driveway, to be specific, under which may lie the solution to a 37-year-old national mystery. whatever happened to jimmy hoffa? and where did they dump the body? it's all marked up. tomorrow, they bring in the digger to rip it open. >> we're strictly investigating this as a cold case homicide. >> reporter: it's always been assumed that hoffa, once the powerful president of the teamsters union, who then did jail time for bribery, was killed off by the mob, after he walked out of this detroit restaurant in july 1975. >> i'm going to do what i got to do! >> reporter: it became the stuff of documentaries and movies, like 1992's "hoffa." over the years, many theories and a few leads. an early one, that hoffa's body